[Nook Color General] skwalas:
After getting a little annoyed at the runty, poorly mapped-out, scratchy thicket of real and imagined performance tweaks, I decided to embark on a semi-long term project to determine what's real and what's "zomg mega-booster performance pills".

First project was to evaluate existing performance options on stock CM10 for actual gains using experimental design. (tl;dr: for those geeky enough to want to know, it was a main effects only d-optimal design with 32 design points for the 16 parameters listed, including several lack-of-fit and pure-error replicates. I could go on, but do you really want me to?). I ended up with a list of 16 parameters all together, from the Developer Options and Performance settings, based on their showing up in various performance tweaks discussions.

The main challenge was finding a way to measure actual performance instead of perception. I settled on several benchmarking tools: Antutu, Quadrant, SQL Benchmark, and Chainfire's benchmarking app. One of the parameters being tested ("don't keep activities") actually breaks Antutu at the graphics testing step, so I'm not reporting anything from Antutu.

All told, out of the 16 parameters tested, only 9 showed any kind of effect whatsoever, and combining best settings for all 9 simultaneously, total performance only boosted by ~20%, of which fully half was due to switching max speed from 1000 to 1100. this means the other 8 settings combined for a total boost of ~10%, meaning individually they're peanuts. The remaining 7 settings that showed no effect are only so much fluff and unlikely to do a thing for you performance-wise.

Results are summarized below for your reading/teeth-gnashing pleasure:

Max Speed (1000 versus 1100): Very clear, notable difference between the two settings on all benchmarks. This is the expected result, about 10% improvement in all benchmarks on average. Recommendation: set max speed at 1100.

Governor (convservative vs interactive vs ondemand): This only had any impact on Quadrant benchmark, no other benchmarks appeared to care. In Quadrant, conservative was the worst overall, while interactive provided an ~ 5% boost and ondemand gave ~6% boost. Recommendation: use ondemand.

Scheduler (BFQ, CFQ, noop, deadline): I don't know what schedulers do or the differences between these settings, but the only place they had any effect at all was in the SQL benchmark. There were clear differences here though: BFQ was by far the worst. CFQ and deadline were about the same with a 17% increase in SQL activity performance. noop was the best with ~ 20% increase in SQL activity performance. Recommendation: use noop. [update: some have reported stability issues with noop. If thus us the case for you, CFQ would be the next best choice]

Zram (disabled, 18% default, 26%): Zram effects only showed up in Chainfire's benchmark app, specifically for Java activities. Default 18% setting performed worst but disabled setting wasn't significantly different. 26% setting gave a 4% boost, but again, only for the java-specific benchmark. Recommmendation: use 26% setting.

16-bit transparency (off or on): Turning on the 16-bit transparency setting gave a smallish 3% boost to Chainfire's java benchmark. It did not have a measureable effect anywhere else, and I did not visually see any differences anywhere during testing. Recommendation: turn on 16-bit transparency.

Kernel same-page merge (off or on): This had a *negative* effect when turned on, resulting in a 1% performance hit on Chainfire's native benchmark. It did not have any measurable effect anywhere else. Recommendation: Keep off.

Don't keep activities (off or on): This was very problematic: it provided a distinct improvement in quadrant score (+8%) when turned on, but behaved poorly with other apps (Antutu being one). Since it didn't seem to help anywhere else outside of Quadrant and didnt' play well with others, recommendation is to keep off:

The following list are the settings that had no measureable impact anywhere. Any attempt to claim they have "zomg" status should be summarily whipped with placebo pills, or else they should let me know the exact details in which they supposedly work and I can test.

Placebo hall of shame:

Surface improvement (since it had no effect anywhere, why not just set it on banding/blur and have the best pictures?)

Background process limit

Disable HW overlays

Force GPU setting

Any of the animation scale settings (although they look snappier at lower settings, so it at least *feels* faster)

minimum speed (seriously? people think this has an effect? keep at 300 for best battery life)

Allow purging of assets

Hope you like this, y'all! Let me know if there's any other mad-scientist experiments you'd like to see.